This study aims to determinate if there is a facial mimicry disorder in PD ( Parkinson's disease )patients with emotional facial expression (EFE) recognition impairment, compared to healthy control subjects. We also want to know if this facial mimicry disorder is primary (subtended by facial mobility impairment, that is to say amimia) or secondary (related to the mirror neuron systems that allows us to activate similar neural networks when observing and feeling a specific emotion)